It's probably the best known mantra in the customer service repertoire: The Customer is Always Right.

We drill into our employees' heads that whatever happens, they need to keep a smile on their face and get through it. It's a feel-good statement; the gold standard for public-facing employees across industries.

It's a reminder to customer service reps the world over that regardless of the situation or specifics, the customer is always right. Always.

It's also dead wrong.

Alexander Kjerulf shared five reasons "The Customer is Always Right" is wrong in a recent Huffington Post article. Chief among them was that this mantra, though well-intentioned, makes employees unhappy, resulting in poorer customer service for all other customers.

Customer service reps are trained in problem solving and dispute resolution, but what do you do when a customer is just flat out wrong and won't back down?

We've experienced this at my software company, WordStream--I'd imagine just about every business has had to deal with a difficult customer who simply couldn't see they were wrong. One that immediately came to mind when I read Kjerulf's column was a B2B client of ours who simply wasn't satisfied with his AdWords account performance. It was one of the top 5% performing accounts in our portfolio.

He repeatedly contacted one of our account managers demanding better results. The team member went to great lengths to explain, but found she was cut off at every turn.

He interrupted. He refused to listen. He insulted her intelligence and was sarcastic and rude. In short, he was the type of nightmare customer front-line workers dread, whether they're in B2B, working in a retail shop, serving food or selling tickets.

Ultimately, she was just being bullied by this customer, who refused to accept that he was wrong.

He simply didn't want to hear her. He wanted her to admit she was wrong so he could be right. They didn't have the same goal and no matter what she did, there wasn't going to be a positive outcome.

"The Customer is Always Right" tells me that despite the fact he was wrong, I should expect my employee to somehow magically become the person in the wrong.

See, when a customer is confrontational and refuses to come down, they've already decided they're right and therefore, you are wrong. Being right is really important to some people--so much so that they'll ignore all logic and reason in a campaign to continue being right.

It's a no-win situation.

Customers, when they're wrong and refuse to accept it, can also suck up a huge amount of your team's time. If you're spending a disproportionate amount of time on one customer, it takes away from productivity and the service you're able to give other customers.

Why do we do this to our employees? It's incredibly demoralizing and the effect can ripple across the entire team.

There's the immediate effect an unhappy employee can have on their next call. (Our rep was so upset at the treatment she received that she had to take a break and regroup). Unhappy people don't give great customer service to the next person.

More harmful though is the tone it sets in your workplace.

Your team has to know and trust that when the chips are down, you will go to bat for them. If you've trained well and have good people in your organization, they're going to go through the process of trying to resolve the situation.

You cannot, after they've done so, tell them, "The customer is always right." The message it sends (to everyone on your team, not only the employee involved) is that they are wrong for doing exactly what you've asked them to do.

It tells your employees you won't stand up for them.

It tells them you don't trust that they did everything they could.

It tells them they can't trust you.

There comes a time when you have to say, we've done all we can for this customer. It doesn't even matter if they think they're right--we cannot afford to continue doing business with them.

We ended up cancelling that client's contract. Losing a customer is never a good thing, but allowing a culture of mistrust to permeate your team is far worse.

If you're with me on that, fire the bottom 10% of your clients every year. Your customer satisfaction and overall revenue numbers will improve in ways you had never imagined!